Collaborative Research: Verification of Atmospheric Mercury Redox Rates

该项目的跨机构合作调查人员将通过定量测量二价汞化合物（汞的水溶性更强的形式），提供一个新的、涉及大气中汞氧化的化合物综合数据集。汞以元素状态排放到大气中，与大气中的氧化剂发生各种反应，变成二价形式，但关于氧化剂种类和这些反应发生的速率存在许多不确定性。该项目的主要目标是使用这些新的汞形态测量，沿着与以前的测量，以定量表征汞的形态和自由基预算的采样羽在湖城地区附近的镁开采设施（美国镁）。两名研究生将在该项目过程中接受培训，项目小组计划向决策者提供有关汞化学及其对人类健康影响的最新信息。该团队还计划与州监管机构合作，以潜在地扩大所获得知识的社会效益。最近与标准测量技术有关的发现揭示了一种系统性的低偏差，这种偏差影响了几乎所有以前对二价汞的测量。该研究小组开发、测试和先前部署的双通道连续汞测量系统可以在没有这种低偏差的情况下进行二价汞测量。这项工作有三个具体目标：（1）对元素汞和二价汞、相关氧化剂以及其他化学和气象变量进行为期一年的测量活动;（2）使用零维F0 AM模型来确定哪些汞化学机制和反应速率使模型测量差异最小化;以及（3）使用F0 AM参数更新GEOS-Chem的汞氧化机制，以尽量减少GEOS-Chem模型测量的差异。这项工作的结果将提高我们对汞化学和受汞化学影响的化学物质的理解，包括卤素、臭氧和氮氧化物。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The cross-institutional collaborative investigators in this project will provide a new comprehensive dataset of compounds involved in the oxidation of mercury in the atmosphere by quantitatively measuring divalent mercury compounds, which are the more water-soluble forms of mercury. Mercury is emitted into the atmosphere in the elemental state, which undergoes various reactions with atmospheric oxidants into the divalent form, but there exist many uncertainties about which oxidant species and what rates these reactions occur. The primary objective of this project is to use these new measurements of speciated mercury, along with previous measurements, to quantitatively characterize both the speciation of mercury and the radical budget of sampled plumes in the Salt Lake City region nearby a magnesium mining facility (U.S. Magnesium). Two graduate students will be trained over the course of this project, and the project team plans on providing policy makers with updated information pertaining to mercury chemistry and the impacts on human health. The team also has plans to engage with state regulators to potentially extend the societal benefits of the knowledge gained.A recent discovery pertaining to standard measurement techniques has revealed a systematic low bias that affects nearly all previous measurements of divalent mercury. The dual-channel continuous mercury measurement system developed, tested, and previously deployed by this research group can make divalent mercury measurements without this low bias. The work has three specific aims: (1) to conduct a year-long measurement campaign of elemental and divalent mercury, related oxidants, and other chemical and meteorological variables; (2) use the zero-dimensional F0AM model to identify which mercury chemical mechanisms and reaction rates minimize model-measurement discrepancies; and (3) update GEOS-Chem’s mercury oxidation mechanism with the F0AM parameters to minimize GEOS-Chem model-measurement discrepancies. Results from this work will enhance our understanding of mercury chemistry and chemical species affected by mercury chemistry, including halogens, ozone, and nitrogen oxides.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.